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The categorization of microbial strains is conventionally based on the molecular method, and seldom are the morphological characteristics in the bacterial strains studied. In this research, we revealed the macromolecular structures of the bacterial surface via AFM mechanical mapping, whose resolution was not only determined by the nanoscale tip size but also the mechanical properties of the specimen. This technique enabled the nanoscale study of membranous structures of microbial strains with simple specimen preparation and flexible working environments, which overcame the multiple restrictions in electron microscopy and label-enable biochemical analytical methods. The characteristic macromolecules located among cellular surface were considered as surface layer proteins and were found to be specific to the Escherichia coli genotypes, from which the averaged molecular sizes were characterized with diameters ranging from 38 to 66 nm, and the molecular shapes were kidney-like or round. In conclusion, the surface macromolecular structures have unique characteristics that link to the E. coli genotype, which suggests that the genomic effects on cellular morphologies can be rapidly identified using AFM mechanical mapping. Graphical Abstract Quantification of surface macromolecules of E. coli cells using AFM mechanical mapping. Surface macromolecules of cellular surface of three E. coli genotypes, MG1655, CFT073, and RS218, were characterized with the sizes ranging from 38 to 66 nm and with round or kidney-like shapes. The topography images were colored with adhesion mapping with the scale bars = 200 nm.

The notion of an effective longitudinal coherence length with its value much greater than λ2/(2Δλ) has been adopted in small-angle X-ray scattering communities for years, where λ and Δλ denote the incident wavelength and its spread, respectively. Often the implications of the effective longitudinal coherence length do not even enter considerations in the designing and data treatment of small-angle scattering experiments. In this work, conventional transmission small-angle X-ray scattering (tSAXS) was performed to reveal a clear angular dependence on effective longitudinal coherence length. The measured values of effective longitudinal coherence length can be as high as one millimeter, whereas the value of calculated λ2/(2Δλ) is in nanometers.

To develop low-power, non-volatile computing-in-memory device using ferroelectric transistor technologies, ferroelectric channel materials with scaled thicknesses are required. Two-dimensional semiconductors, such as molybdenum disulfide (MoS 2 ), equipped with sliding ferroelectricity could provide an answer. However, achieving switchable electric polarization in epitaxial MoS 2 remains challenging due to the absence of mobile domain boundaries. Here we show that polarity-switchable epitaxial rhombohedral-stacked (3R) MoS 2 can be used as a ferroelectric channel in ferroelectric memory transistors. We show that a shear transformation can spontaneously occur in 3R MoS 2 epilayers, producing heterostructures with stable ferroelectric domains embedded in a highly dislocated and unstable non-ferroelectric matrix. This diffusionless phase transformation process produces mobile screw dislocations that enable collective polarity control of 3R MoS 2 via an electric field. Polarization–electric-field measurements reveal a switching field of 0.036 V nm −1 for shear-transformed 3R MoS 2 . Our sliding ferroelectric transistors are non-volatile memory units with thicknesses of only two atomic layers and exhibit an average memory window of 7 V with an applied voltage of 10 V, retention times greater than 10 4  seconds and endurance greater than 10 4 cycles. Rhombohedral-stacked molybdenum disulfide with sliding ferroelectric behaviour can be used to create atomically thin ferroelectric transistors for computing-in-memory device applications.

The discovery of interfacial ferroelectricity in two-dimensional rhombohedral (3R)-stacked semiconductors opens up a new pathway for achieving ultrathin computing-in-memory devices. However, exploring ferroelectricity switching in natural 3R crystals is difficult due to lack of co-existing 3R stacking domains. Here, we present that MoS2 homoepitaxial patterns with 3R polytypic domains can manifest switchable ferroelectricity at room-temperature. Based on the diffusion limited aggregation theory, such MoS2 patterns are formed under the low Mo chemical potential and low temperature with respect to common chemical vapor deposition synthesis. The alternation of 3R polytypes in the MoS2 homoepitaxial patterns, observed by scanning transmission electron microscopy, accounts for ferroelectricity switching. The MoS2 field-effect transistors with 3R polytypic domains exhibit a repeatable counterclockwise hysteresis with gate voltage sweeping, an indication of ferroelectricity switching, and the memory window exceeds those measured for compact-shaped 3R bilayer devices. This work provides a direct growth concept for layered 3R-based ferroelectric memory.